Re: PostgreSQL versus MySQL for GPS Data

On Tue, Mar 17, 2009 at 5:25 AM, Juan Pereira
<juankarlos.openggd@gmail.com> wrote:
> Hello,
>
> The question is: Which DBMS do you think is the best for this kind of
> application? PostgreSQL or MySQL?

Another advantage pgsql has is that many ddl operations on tables do
NOT require exclusive locks on those tables.  Creating indexes, adding
/ dropping columns in mysql will lock the whole table and adding
dropping columns will rewrite the whole table.  In pgsql adding and
dropping columns is almost immediate, and you can create indexes
concurrently so that the table you're creating the index on is not
locked.  This is a big deal on a large production system where index
creation could take anywhere from several minutes to several hours.

Note that almost all ddl is transactable as well, so testing big
schema changes is much safer in pgsql, where you can rollback just
about anything except create / drop database / tablespace.